Power transmission device



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POWER TRANSMISS ION DEVICE IN V EN TOR.

/fe/mm ((//Mm Patented June 20, 1944 UNITED STATE `IOWEB TRANSMISSIONDEVICE Herman W. Drlehaus, Chicago, Ill., assignor to GoodmanManufacturing Company, Chicago, Ill., a corporation of IllinoisApplication February 5, 1943, Serial No. 474,781

9 Claims. This invention relates to improvements in pow- 'ertransmission Ydevices and more particularly relatesto an improvedautomatic power transmission device particularly adapted to transmitpower from a fluid motor to a turntable of a kerf-cutting machine.

The present invention relates to a power transmission device somewhatsimilar to that shown and described in an applicationSerial No. 422,789,filed by William W. Sloane on December 13, 1941, but instead of relyingupon a centrifugal clutch to change the speeds -of the driven member ofthe power transmission device, utilizes a novel form of fluidl pressurecontrol for changing the speeds transmitted by the powertransmissiondevice, as the speeds of rotation of the drive motor therefor arechanged.

The principal objects of my present invention are to provide asimplified form of power transmission device in the drive between afluid motor and a turntable of a kerf-cutting machine wherein the speedof the motor is varied to turn the turntable at slow cutting speeds andat a higher positioning speed, and in so arranging this powertransmission device that a reduction in speed of a driven member thereofwill be obtained when the motor is operating at a slow speed, and thedriven member Will be driven at the speed of rotation of the motor whenthe motor is operating at higher speeds, to take care of inefficienciescaused by leakage of fluid when the motor is rotating at a slow cuttingspeed and to provide an efficient drive from the fluid motor at allspeeds of rotation thereof.

A more specific object of my invention is to provide a novel form ofpower transmission device and fluid controls therefor, and in soarranging the fluid controls as to automatically shift the powertransmission device to drive its driven member at a higher or lowerspeed, as the speed of the fluid motor is changed.

Other objects of my invention will appear from time to time as thefollowing specification proceeds and with reference to the accompanyingdrawings wherein:

Figure 3 is a longitudinal sectional view taken through the drive to theturntable;v

Figure 4 is a plan view of the power transmission device with certainparts broken away and with certain other parts shown in horizontalsection;

, Figure 5 is a transverse sectional view taken substantially along line5 5 of Figure 4;

Figure 6 is an enlarged detail sectional view of the fluid cylinder andpistonfor operating the power transmission device, showing the piston ina, different operating position than in Figure 4;

Figure 7 is a diagrammatic view showing the fluid connections, fordriving the fluid motor at 4either a low speed or at aplurality ofpredetermined higher speeds, and for controlling operation of the powertransmission device; and

Figure 8 is an enlarged detail view in side elevation, showing certaindetails of the control mechanism for the valves, for controllingoperation of the turntable and power transmission device.

In the drawings, the embodiment of my invention illustrated is shown asforming a power drive means for a turntable II of a kerl-cutting machineof the track-mounted type, for turning said turntable and laterallyswinging a chain carrying cutter bar I3 projecting therefrom, across acoal face. Said cutter bar extends from a cutting element generallyindicated by reference character I4 and is adjustable with respectthereto and with respect to said turntable to cut a horizontal kerfacross a coal face upon feeding movement thereacross by said turntable.`'I'he kerf-cutting machine herein illustrated is of a usual typeoftrack-mounted cutting machine commonly known as a slabbing machine.somewhat similar to that illustrated in application Serial No. 369,194,filed by William W. Sloane on December 9, 1940, and is no part of mypresent invention so will not herein be shown or de- Figure 1 is a planview of a kerf-cutting machine of the track-mounted type having a fluidscribed in detail.

The drive to the turntable includes a fluid motor I5 of a well knowngear type and supplied with fluid under pressure by means of either oneor both of a pair of fluid pumps I6 and I'I. Said fluid pump I6 is of alower capacity than the fluid pump I1 and is adapted to drive said motorat a slow feeding speed. Said fluid pump I1 is adapted to supply agreater volume of fluid to the motor I5 than the pump I6, to drive saidmotor at an intermediate feeding speed.A Said second mentioned pump maybe used for driving said motor where the cutting is relatively soft andthe feeding speed of the cutter bar can safely be increased over thatimparted by the pump I6. Both of said fluid pumps acting together areadapted to drive said motor at a higher positioning speed, to positionsaid cutter bar for cutting and to move said cutterbar back and forthacross a kerf cut in a coal face to cause said cutter bar to rake anyloose cuttings or slate therefrom.

The iiuid motor I5 has direct driving connection with a powertransmission device I9 through its motor shaft. Said power transmissiondevice` in turn has driving connection with a driven member 2|, hereinshown as being a longitudinal shaft keyed to.a cage 22 of a planetarygeared reduction device 23, forming part of said power transmissiondevice (seeFigure 4). The shaft 2| has a worm 24 formed integrallytherewith which meshes with a worm gear 25 on a transverse shaft 26 (seeFigures 2 and 3). A worm 21 on said transverse shaft meshes with anddrives a worm gear 28 on a vertical-shaft 29. A spur gear reductiongenerally indicated by reference character 38 is provided to connectsaid vertical shaft with gear teeth 3| cut on the outer periphery ofsaid turntable, for driving said turntable (see Figures 2 and 3).

Referring now to Figure 4, illustrating certain details of the powertransmission device I9, a

ings 48, mounted within said sleeve 34. Said shaft extends Within acasing 43 of the planetary geared reduction device and is journaled insaid casing at its end opposite the motor I5, on a ball bearing 44. Saidball-bearing is mounted within the cage 22 of the planetary gearedreduction device 23, which cage is keyed to the shaft 2| and isjournaled on its hub within an end frame member 5B of said casing.

The planetary geared reduction device 23 includes a spur sun gear 45,keyed onl the shaft 31 just inside .of the ball bearing 44 and meshingwith a planetary pinion 46. Said planetary pinion is freely mounted on alongitudinally extending shaft 41, which is mounted at its opposite endsin the cage 22. Said planetary pinion meshes with an internal gear 49,herein shown as being cut integrally Withthe inside of the end framemembers of the casing 43. Said end frame member is secured to saidcasing by means of cap screws 5I, 5|.

A friction brake 53, herein shown vas being a multiple disk type offriction brake, is provided to hold the casing 43 from rotation, tocause the planetary pinion 46 to be orbitally driven about the internalgear 49 by the sun gear 45. This will rotatably drive the cage 22 andshaft 2| at a reduced speed. When the brake 53 is disengaged, theinternal gear 49 and casing 43 will be free to rotate.

A friction disk clutch 55 is provided within the casing 43 to form ameans for rotatably driving tation of the motor shaft 33, the planetarypinions 46, 46 andthe cage 2| rotating as a unit with said casing 43, todrive said shaft 2| therewith at the speedof said shaft 31.

The brake 53 includes a plurality of alternately arranged annularfriction disks 56 and 51. The disks 56, 56 are internally splined andthe splined portions thereof have engagement with an externally splinedmember 59, herein shown as being feather keyed on the end of the sleeve34 adjacent the motor I5. The` disks-51, 51 are externally splined andthe splined portions thereof have engagement with an internally splinedportion of an annular frame member 53, which is 'secured to an end plateof the motor I5 and is adapted to hold said disks from rotation. Anannular retaining member 64 mounted on a ilange 65 of the splined member59 abuts the end disk 56 adjacent the motor l5. An annular abuttingmember 66 abuts the opposite end disk 56 and serves to apply saidfriction brake or permit it to be released. Said abutting member ismounted on its hub on an engaging member 61, which is slidably mountedon the sleeve 34.

A ball bearing 68 is mounted on the outside of the engaging member 61and abuts a shouldered portion 69 thereof at one of its sides, and abutsthe annular abutting member 66 at its opposite side. Said bearing ismounted in a split housing 6|, which also serves as a shifting memberfor the brake and encircles the hub of the engaging member 61 and thehub of the abutting member 66, f

The end of the engaging member 61 opposite Ii'rom the motor I5 is of anannular flanged formation, facing an end plate 18 ofthe casing 43, whichend plate is herein shown as being formed integral with the sleeve 34and is secured to the' end of said casing 43 by cap screws 1I, 1|. Saidanged portion of said sleeve is provided with a plurality of sockets 14,14 adapted to receive springs 13, 13. Said springs have engagement withsaid end plate -10 and serve to move the engaging member 61 and abuttingmember 66 in a direction to hold the friction disks 56 and 51 inengagement with each other and to apply the brake 53. y

The brake 53 is released by means of a shifting ring 12, operativelyconnected with the housing 6| and pivotally connected to a bracket 15projecting horizontally from the annular frame 63 in a direction towardsthe planetary unit 23. Said shifting ring is connected to said bracketby means of a lug 16, projecting outwardly from said ring and pivotallyconnected to said bracket by means of a vertical threaded pin 11, havinga nut 18 threaded on its lower end. A bifurcated lug 19 projects fromthe side of said shifting ring opposite from the lug 16 and is plvotallyconnected to the free end of a piston rod 80 by means of a pivotal pin8|. vSaid piston rod serves to operate said ring and extends .from apiston 83, movable within a fluid cylinder 64. Said fluid cylinder ismounted on a bracket 35, projecting from the annular frame 63.

The piston rod 88 is mounted in a flanged socket 81, slidably mountedwithin a cylindrical portion 86 of the piston 33. The inner side of saidsocket is encircled by a compression spring 83 which abuts the angedportion of said socket at one of its ends. Said socket is retained insaid piston by a. iianged retaining nut 89 threaded within the outer endof said piston and engaging the flanged portion of said socket. 'I'heopposite end of said spring abuts an outwardly exasume 3 tending flangeof a sleeve 90 mounted in the inner end of said cylindrical portion 99of said piston. Saidl flanged sleeve has an internally flanged portionwhich is engaged by a compresal sion spring 92. The opposite end of saidspring 92 engages a head of a retaining screw 99, threaded within a boss94 extending inwardly from a head end 95 of said piston. A packingmember Il is interposed between said cylindrical portion and said headend of said piston. l

Said packingmember is held in compressionby said spring 92 and serves tohold said packing member in compression and to prevent leakage od i'luidby said piston. A nut 9| threaded in the ,end of said cylinder isadapted to engage a shouldered portion lof said piston and limitmovement thereof. l

It is apparent from the foregoing that the shifting ring 12 is shiftedthrough the spring 90. In Figure 6 it may be seen that the travel of thepiston 99 is greater than the travel of said shifting ring. 'Ihe brake53 is thus held in an engaged position by said compression spring, heldin compression by fluid under pressure within the cylinder I4. Thus anywear of said brake 4may be taken up by said spring, rendering adjustingmeans to take up for wear of the brake unnecessary.

The shifting ring 12 has a pair of coaxial vertical pins 91,k 91extending inwardly from opposite sides thereof.' The inner ends of saidpins are mounted in bosses 99, 99 formed integrally with the outside ofthe housing and projecting therefrom towards the end plate 10. Saidlhousing thus forms a means for disengaging the brake 59 through the ballbearing 69 and annular abutting member 69, when fluid under pressure isadmitted to the cylinder 94.

The iluid cylinder 94 and piston 99 also serve to apply the frictionclutch 55 upon release of the brake 53, through pins 99, 99 mounted in"the end face of the flanged portion of the engaging member 61 andextending therefrom in parallel relation with respect to the shaft 91.Said pins extend from said ilanged portion of said engaging memberthrough the end plate and are adapted to engage an end engaging plate|00 ofsaid friction clutch. When fluid under pressure is applied to saidpiston, said pins will engage and move said end plate |00 of saidfriction disk clutch in a direction to-engage alternately arranged disks|0I, |0| and |02,-|02 of said clutch with each other, to rotatably drivethe casing 49 at the speed of rotation of the shaft through a splineddrive member |09 keyed on said shaft.

The friction disks 0|, |0I are internallysplined and the splines thereofhave engagement with the splined driving member |03. The disks |02, |02arranged alternately with said disks |0|, |0| are externally splined,and the splines' thereof have engagement with splines |04, |04 formedinternally of the casing 43, for rotating said casing with said shaftwhen said disks are in i an engaged position. An abutment member |0| ais mounted on said drive member |09 and is adapted to abut an end disk|0| of said clutch, to form a reaction member for said clutch.

Referring now in particular to Figure 7 and the fluid connections forsupplying iiuid under pressure from either one or both of the pumps I0and |1 to the motor I5, a fluid storage tank |09 is provided. A pressureline |06 leads from said tank and is connected with a branch line |01,which is connected at its opposite ends said pumps |9'and |1. A pressureline |09 leads from the pump i6 to a valve |09. Said valve may beof anywell known type, but is herein shown as being a balanced pressure spooltype of valve. A pressure line ||0 leads from said valve to the pressureside of the fluid motor I5. to supply fluid under pressure to saidmotor, to. drive said 'motor from the pump I6 at a relatively slowspeed.

A discharge line leads from the motorl I5 to the valve |09 and is alsoconnected to a valve 2. which valve is connected with the fluid pump |1to supply fluid under pressure to said motor from saidl pump. A lowpressure line ||9 leads from the discharge side of the valve 09 to thedischarge side of the valve ||2. Said low pressure line has connectionwith a return line ||4 leading tothe tank |05. The valve |`|2 isconnected to the pump |1 through a pressure line ||5 and has connectionwith the pressure side of the motor I5, through a pressure line ||6connected to the pressure line ||0 leading from the valve |09.

When the-valve |09 is closed and the valve ||2 is open, the motor I5will be driven from the pump |1 at an intermediate feeding speed, andwhen both valves |09 and ||2 are open, the motor will be driven at ahigh speed, which may be used for positioning the cutter bar for cuttingacross a face, or for moving the cutter bar back and forth in a kerfwhich has already been cut, for raking slate or loose cuttingstherefrom.

The fluidA connections to the fluid .cylinder 94 for supplying fluidunder pressure thereto inlclude a pressure line ||1 connected to thepressure line ||5 and leading to a pair of valves ||9 and ||9, which areherein shown as being connected together in series. A pressure line |20leads from the valve ||9 to said uuid cylinder 04. A return line |2| isconnectedl from the valve ||9 to the tank |05. A line |22 connects thevalve ||9 to said return line.

The valves H9 and ||9 are mechanically connected with the respectivevalves ||2 and |09, to open together when said valves |09 and I|2 areopened to a' position to admit fluid under pressure to drive the motorI5 from the pumps I6 andA I1. Said valves ||9 and ||9, however, are notopened to drain except when the respective valves ||2 and |09 are inneutral positions. When said valve Ill is open to let iluid underpressure pass therethrough, and the valve |09 is closed, the valve ||9will be closed to prevent fluid from entering the pressure line |20 andfluid cylinder 94.' When the valves |09 and ||9 are open, and the valveI|2 is closed, the valve ||8 will also be closed to prevent the passageof fluid to the cylinder 94. Thus iluid can only enter the uid cylinder84, to change the speed of the driven member, -when the motor' I5 isdriven through both of the pumps I6 and |1.

In Figure 2 the valve ||9 is shown as being mounted directly above thevalve ||2 and the valve ||9 is shown `as being mounted directly abovethe valve |09. The mechanical connections between said valves ||2 and 9and said valves |09 and ||9 are similar, so the connection be- 4 eitherside of the machine. A pin |24 extends throughsaid rod, intermediate itsends,I and projects beyond the sides thereof and extends within slots|25, |25 formed in the furcations of a bifurcated lever arm |26. Thelower end of said lever arm is pivotally connected between thefurcations of a bifurcated connecting member |2'|, secured to the end ofa stem |28 of the valve |819; A link |29 is pivotally connected to a lug|30 projecting from a head |3| of said valve |09 and has piv' otalconnection at its opposite end to the lever arm |26, intermediate itsends. Thus movement of the valve operating rod |23 in a direction',which in Figure '7 is shown as being to the right, will open the valve|09 to permit fluid to pass from the pump I6 to the motor I5.

The valve ||9 is operated by the valve operat ing rod |23 by means of apin |32 depending from a plate |33 secured to the bottom of said valveoperating rod, and extending therealong for a short part of its length.Said pin is adapted to have slidable engagement with a slot |34 frformed in an arm |35 projecting outwardly from a cam |36 (see Figure2'). Said cam is: mounted on a vertical shaft |31, and has engagementwith |38 is in engagement with the high spot of said cam, said pistonwill be moved against said spring to open said valve. ment of the valveoperating rod |23 in a direction, which is shown in Figure 8 as being tothe right.

The valve |2 is operated by means of a transversely extending valveoperating rod |44, similar to the valve operating rod |23. The operativeconnection between said valve operating rod and said valve is the sameas the connection from the valve 'operating rod 23 to the valve |09. Acam |45, operated through a pin |46 depending from the rod |44, isprovided to operate said valve 8 upon operation of said valve ||2.

It may be seen from the foregoing that a novel form-of transmissiondevice has been provided for transmitting power from a fluid motor,which under pressure from either one or the other of f the pumps I6 orthe driven shaft of the power transmission device will be driven throughthe planetary 23 at a slower speed than the speed of rotation of the uidmotor, but that 'when said uid motor is driven at a high rate of speedthrough both of the pumps I6 and the speed of rotation of the drivenshaft will be the same as the speed of rotation of the fluid motor. Itmay further be seen that this power transmission device is automaticallyoperated upon connection of the two pumps |6 :and I1 to the fluid motorI5 and that as soon as one or This is effected upon movethe other ofsaid pumps is disconnected from While I have herein shown and describedone form in whichmy invention may be embodied. it will be understoodthat the construction thereof and the arrangement of the various partsmay be altered without departing from' the spirit and scope thereof.Furthermore, I do not wish to be construed as limiting my invention tothe specific embodiment illustrated, excepting as it may be limited inthe appended claims.

I claim as my invention: v

1. `In a hydraulic power transmission device, a uid motor having a motorshaft, means for supplying uid to said motor under different volumes, tocontrol the` speed of rotation thereof including a pair of selectivelyoperable uid valves, -a driven shaft, a geared reduction meansinterposed between said motor shaft and said driven shaft, fluidactuated means for controlling operation ofA said geared reductionmeans, and a pair of valves controlled by operation of said rstmentioned valves and having operative connection with said fluidactuated means, for supplying uid under pressure thereto to connect saidtransmission device to drive said driven shaft at a reduced speed whenone or the other of said rst mentioned valves is open, to supply fluidto drive said motor at-a plurality of low speeds, and to connect saidgeared reduction device to drive said driven shaft at the speed of saidmotor shaft, when both of said rst mentioned valves are open to drivesaid motor at a predetermined high speed.

2. In a hydraulic power transmission device, a uid motor having a motorshaft, a plurality of fluid pumps for supplying fluid to said motor atdifferent volumes to cause said motor to rotate at different speeds, aplurality of selectively operable fluid valves, for controlling theconnection of any one or all of said fluid pumps to said motor, a drivenshaft, a geared reduction means interposed between said motor shaft andAsaid driven shaft, fluid actuated means for controlling operation ofsaid geared reduction means, and a plurality of fluid valves controlledby operation of said first mentioned valves and hav` duction means whenany one of said valves is.'

open, to supply uid under pressure to kdrive said motor at predeterminedlow speeds, and` to connect said transmission device to drive saiddriven shaft directly through said motor shaft when all of said valvesare open to drive said motor at predetermined high speeds.

3. In a hydraulic power transmission device,

a fluid motor having a motor shaft, a plurality of fluid pumps forsupplying fluid to said motor at different volumes to cause said motorto rotate at different speeds, a plurality of selectively operable fluidvalves, for controlling the connection of any one or all of said fluidpumps to said motor, a driven shaft, planetary reduction meansinterposed between said motor shaft and said driven shaft, a cylinderand piston for controlling operation of said planetary reduction means.and a plurality of fluid valves controlled by operation of said firstymentioned valves to control the supplying of fluid underpressure to saidcylinder and piston to cause said driven shaft lto be driven throughsaid planetary reduction means when said motor is rotating at a lowspeed, and to cause said driven shaft to be driven at the speed of saidmotor shaft as the speed of aas-i346 salici motor is increased to apredetermined value.

44. In a hydraulic power transmission device, a fluid motor having amotor shaft, a plurality of fluid pumps for supplying fluid to saidmotor at different volumes to cause said motor to rotate at differentspeeds, a plurality of selectively operable fluid valves, forcontrolling the connection of any one or all of said fluid pumps to saidmotor, a driven shaft, planetary reduction means interposed between saidmotor shaft and said driven shaft, a cylinder and piston for controllingoperation of said planetary reduction means, a fluid valve associatedwith each one of said flrst mentioned valves and mechanically connectedtherewith to open as said first mentioned valves are opened, .to supplyfluid under pressure to said cylinder and piston when all of said firstmentioned valves are opened, to cause said piston to connect saidtransmission device to drive said driven shaft at the speed of saidmotor shaft, when said motor is driven from all of said pumps, and forreleasing fluid pressure from said cylinder and piston when said motoris driven from any one of said pumps, to connect said transmissiondevice to drive said driven shaft through said planetary when said motoris rotating at a predetermined slowspeed.

5. In a hydraulic power transmission device, a fluid motor having amotor shaft, two fluid pumpsifor supplying fluid to said motor atdiiferent volumes to cause said motor to rotate at different speeds, twoselectively operable fluid valves for connecting any one or all of saidpumps to supply uid under pressure to said motor, a driven shaft,planetary reduction means interposed between said motor shaft and saiddriven shaft, fluid actuated means for controlsaid motor is operating ata high speed, and to release fluid from said fluid actuated means tocause said driven shaft to be driven through said planetary means whensaid motor is operating at a low speed.

6. In a hydraulic power transmission device.'

a fluid motor having a motor shaft, two :duid

pumps for supplying fluid to said motor at different volumes to causesaid motor to rotate at different speeds, two selectively operable fluidvalves for connecting any one or both of said pumps to supply fluidunder pressure to said motor, a driven shaft, planetary reduction meansinterposed between said motor shaft and said driven shaft, a uidpressure cylinder and piston for controlling operation of said planetarymeans, a pair of uid valves for supplying fluid under pressure to saidfluid pressure cylinder and piston, and means operable upon operationmission device to drive said driven shaft at the speed of said motorshaft when said fluid motor is driven by both of said pumps, and torelease fluid from said fluid actuated means when said fluid motor isdriven throughone of said pumps at a low speed, to cause said drivenshaft to be driven through said planetary means.

7. In a hydraulic power transmission device, a fluid motor having amotor shaft, a plurality of fluid pumps for supplying fluid to saidmotor at different volumes, to cause said motor to rotate atA differentspeeds, a plurality of selectively operable fluid valves, forcontrolling the connection of any cme or all of said .uidpumps to saidmotor, a driven shaft, planetary reduction means interposed between saidmotor shaft and said driven shaft, lsaid planetary reduction meansincluding a reaction member, means for holding said reaction member fromrotation, while said motor is rotating at a slow speed, and means forrotating said reaction member at the speed of said motor as said motoris driven at a high speed through all of said uid pumps,

said last mentioned means including a clutch, fluid actuated means forreleasingA said holding means and applying said clutch, a plurality ofvalves connected in series for controlling operation`of said fluidactuated means, each one of said valves being connected with one of saidfirst mentioned valves and being operabletherewith, to open upon openingof said first mentioned valves, said last mentioned valves being soconnected together as to permit fluid to pass to said fluid actuatingmeans only when all of said first mentioned valves are open, to connectall of said pumps to said motor.

8. In a hydraulic power transmission device, a fluid motor having amotor shaft, two uid pumps for supplying fluid to said motor atdifferent volumes to causeA said motor to rotate at different speeds,two selectively operable fluid valves for connecting any one or all ofsaid pumps to supply fluid under pressure to said motor, a driven shaft,planetary reduction means interposed between said motor shaft and saiddriven shaft, said planetary reduction means including a reactionmember,`a friction brake for holding said reaction member from rotation,a friction clutch for rotatably driving said reaction member with saidmotor, and means for releasing said brake and applying said clutch whenboth of .said pumps are driving said fluid motor at a predetermined highspeed including a fluid pressure actuating means having operativeconnection with said clutch and said brake, two valves connected inseries, for controlling the passage of fluid to said actuating means,said valves being operable upon rotation of said rst mentioned valves topermit lthe passage of fluid to said actuating means only when both ofsaid pumps are connected to drive said motor at a high speed.

of said first mentioned valves, for operating said second mentionedvalves when said rst mentioned valves are positioned to cause both pumpsto supply uid under pressure to said motor,

[to supply fluid under pressure to said fluid pressure cylinder andpiston to cause said uid pressure cylinder and piston to connect saidtrans-v 9. In a hydraulic power transmission device, a fluid motorhaving a motor shaft, two :fluid pumps for supplying fluid to said motorat different volumes to cause said motor to rotate at different speeds,two selectively operable fluid valves for connecting any one or allofsaid pumps to supply fluid under pressure to said motor, a driven shaft,planetary reduction means interposed between said motor shaft and saiddriven shaft, said planetary reduction means including a reactionmember, a friction brake for holding said reaction member from rotafion,a friction clutch for rotatably driving said reaction member with saidmotor, and means for releasing said brake and applying said clutch whenboth of said pumps are driving said fluid motor at a predetermined highspeed including a uid pressure actuating means having operativeconnection with said clutch and said brake, two valves connected inseries, for controlling the passage of uid to said actuating means, andmechanical connections between said mst and second mentioned pairs ofvalves, to cause said second mentioned valves to open upon ,opening ofsaid rst mentioned valves. said second mentioned valves being connectedtogether in series to prevent the passage of uid to said iuid pressureactuating means except when both of said ilrst mentioned valves are opento drive said motor by both of said pumps.

` HERMAN W. DRIEHAUS.

